where \(\bar{\epsilon }=r_1-\delta \)  (this is the parameter in the kinetics mixing in the notation of Ref. [1]}) and as in the case of the model in the previous section, when \(\phi =0\) , then \(\psi =0\)  and the dark sector decouple from the SM particles.
Thus, this model actually becomes secluded and is similar to that in Sec. . Thus, there is no millicharged dark matter in this case. However, in this case \(\tan \phi =0\)  means, according to Eq. (REF ) that \(\epsilon =\delta \)  and then it is possible to have a bare mass for the vector boson \(B\)  but the dark sector decouple from the SM particles.
